Method of fabricating epitaxial structures

Abstract

A method of fabricating epitaxial structures including applying an etch stop to one side of a substrate and then growing at least one epitaxial layer on a first side of said substrate, flipping the substrate, growing a second etch stop and at least one epitaxial layer on a second side of the substrate, applying a carrier medium to the ultimate epitaxial layer on each side, dividing the substrate into two parts generally along an epitaxial plane to create separate epitaxial structures, removing any residual substrate and removing the etch stop.

Description

FIELD OF THE INVENTION[0001]This invention relates to a method of fabricating epitaxial devices.BACKGROUND OF THE INVENTION[0002]Fabricating epitaxial structures such as solar cells, LED's, lasers and IR cells is costly and complex. Solar cells have been fabricated forming inverted metamorphic (IMM) cells, by depositing the layers such as InGaP, GaAs, and InGaAs on a wafer or substrate such as GaAs often resulting in an array of a multiplicity of solar cells and then applying a carrier and removing the substrate by side etching it away. This process is slow and difficult and can result in poor and inconsistent performance. After removal of the substrate the processed epitaxial layers may be sawed into the individual solar cells. Solar cells have also been made by singulating the multiplicity of cells on, for example, a four inch wafer and then applying a carrier. The individual cells are then lifted off the substrate by etching along the singulation lines and underneath the individu...

AI Technical Summary

Benefits of technology

[0003]In accordance with various aspects of the subject invention in at least one embodiment the invention presents an improved method of fabricating epitaxial structures which reduces the number of substrates required for the fabrication process by a factor of two and which admits of a simple and direct removal of the substrate, and the use of a number of different carriers including metals, which does not require singulation before separation from the substrate, and is compatible with further processing.

Problems solved by technology

Fabricating epitaxial structures such as solar cells, LED's, lasers and IR cells is costly and complex.

This process is slow and difficult and can result in poor and inconsistent performance.

The individual cells are then lifted off the substrate by etching along the singulation lines and underneath the individual cells This process is not optimal for mounting onto metal carriers and the individual cells so formed are difficult to process and handle.

Often another material such as epoxy is incorporated, and further processing as well as final cell performance may be limited.

Another shortcoming of such processing is that the wafers or substrates on which the epitaxial layers are grown, is often damaged or rendered unable to be reused, eliminating the cost benefits of epitaxial removal and substrate reuse.

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